In line with a trend of increasingly smaller and lighter electronic apparatuses, smaller high-frequency capacitors with large capacitance are demanded. Solid electrolytic capacitors that have low equivalent series resistance (ESR) and good frequency characteristic have been developed as this type of capacitors. A solid electrolytic capacitor includes an anode formed of valve action metal, such as tantalum, niobium, titanium, and aluminum; a dielectric layer formed on a surface of the anode, and a solid electrolytic layer formed on a surface of the dielectric layer.
As a solid electrolytic layer, formation of a conductive polymer layer on the surface of the dielectric layer has been proposed (e.g., PTL 1 and PTL 2). The conductive polymer layer is known to establish insulation (high resistance) at a required part by locally generating Joule heat when excessive leak current runs between the anode and a cathode of the conductive polymer layer. This function of the conductive polymer layer is also called a self-repair capability with respect to its suppression of the leak current.